Buoys are used, for examples, as markers to locate fishing traps, as floats to support a fishnet in a fishing area or as markers for navigational points of reference. These buoys are transported by boats to and from a fishing area and stored in a dry place during the off-season periods.
The design of a buoy is done by giving the buoy sufficient volume to provide a required buoyancy. Although the volume of the buoy is not a concern when the buoy is in use on a body of water, it can cause difficulties during the transport and storage of the buoy. When the buoys are relatively large, it takes more trips to deploy a number of them, and more space in a warehouse to store them.
Although there is an incentive to make marine buoys stackable, the prior art literature is very limited in this field. It is believed that the prior art does not contain a practical design for a stackable buoy that is suitable for the fishing industry.
Examples of the prior art stackable buoys are:    U.S. Pat. No. 3,060,463 issued to L. I. Pentzien on Oct. 30, 1962;    U.S. Pat. No. 4,936, 804 issued to M. R. Dowdeswell on Jun. 26, 1990;    U.S. Pat. No. 5,350,330 issued to G. W. Platis on Sep. 27, 1994;    CA Patent 933,818 issued to C. D. Inman on Sep. 18, 1973;    CA Patent 879,815 issued to S. N. Schlein on Aug. 31, 1971;
The above prior art floats and buoys have either a tapering skeletal structure or a shell-like form. In both types, their ratio of buoyancy over volume is relatively small, which makes them inappropriate for use in commercial fishing applications.
Therefore, it is believed that a market demand still exists for a stackable buoy that has a form that can displace a relatively large volume of water, and that can be transported and stored in a space that corresponds to only a portion of its actual volume.